Bigelow & Dressler1 reported on the design and construction of IMACS - the Inamori-Magellan Areal Camera and Spectrograph. IMACS was installed on the Magellan-Baade 6.5-m telescope at the Carnegie Institution's Las Campanas Observatory in Chile in August, 2003, and was phased into regular operation in the remaining months of that year (Osip et al2). IMACS is now the most-used instrument on the Baade telescope, accounting for 63% of the nights available for astronomy in the 2005 observing year.
IMACS has two basic operating modes. A single 6-inch beam refractive collimator feeds either (1) an f/4 all-spherical refractive camera delivering 0.11 arcsec/pixel, or (2) a double-asphere refractive camera with oil-coupled multiplets producing a scale of 0.20 arcsec/pixel. The detector for both foci is an 8K x 8K mosaic camera of 8 SITe 2K x 4K 15 μ CCDs. The collimator and f/4 camera have performed to design specifications and have delivered 0.45 arcsec images across the 15 arcmin square field. The f/2 camera has delivered images of 0.55 to 0.65 arcsec across its 27 arcmin diameter field in excellent seeing (FWHM ~ 0.40 arcsec). The f/4 camera uses 6-inch reflecting gratings to obtain spectroscopy at multiple resolutions ranging from R=1350-9375; the f/2 camera uses three 6-inch grisms to achieve resolutions of R=450, 600, and 900 over its larger field. We routinely cut hundreds of slits in 30-inch diameter, stainless steel, spherical-shell slitmasks with a commercial laser system. Alignment procedures for observing are simple and efficient, typically requiring 5-10 minutes per set-up.
IMACS - an unusually versatile instrument - includes an IFU built by Durham University with two 5" x 8" (f/2) or 4" x 7" (f/4) apertures, each sampled by 1000 optical fibers. A Multi-Object Echelle mode, which can obtain 10-15 full wavelength R=20000 spectra, has been fully tested and has now started regular operation. The Maryland-Magellan Tunable Filter (MMTF) has been lab tested and will be commissioned in June 2006. In early 2007, Gladder's Image-Slicing Multislit Option (GISMO) will be ready for testing, and a second Mosaic CCD camera - which will simplify operations, increase sensitivity, and allow rapid access to both f/2 and f/4 modes - is under construction.
We report on the design challenges posed and met by the variety of operating modes and stringent performance requirements. We describe some issues encountered in the past two years in bringing such a complex, multi-mode instrument to the Magellan Observatory.
The Terrestrial Planet Finder Coronagraph (TPF-C) is a deep space mission designed to detect and characterize Earth-like planets around nearby stars. TPF-C will be able to search for signs of life on these planets. TPF-C will use spectroscopy to measure basic properties including the presence of water or oxygen in the atmosphere, powerful signatures in the search for habitable worlds. This capability to characterize planets is what allows TPF-C to transcend other astronomy projects and become an historical endeavor on a par with the discovery voyages of the great navigators.
The Magellan Telescopes are a collaboration between the Observatories of the Carnegie Institution of Washington (OCIW), University of Arizona, Harvard University, University of Michigan, and Massachusetts Institute of Technology (MIT) consisting of two 6.5 meter telescopes located at Las Campanas Observatory, in the Chilean Andes. The Walter Baade telescope achieved first light in September 2000 and the Landon Clay telescope started science operations in September 2002. In addition to two modified spectroscopic instruments, the Boller and Chivens Spectrograph and the Low Dispersion Survey Spectrograph (LDSS-2), four first generation instruments are now deployed at the Magellan Telescopes. Here we briefly describe the operations and performance of MagIC - a direct imaging CCD camera, MIKE - a double echelle spectrograph, PANIC - a near-IR imager, and IMACS - a multi-purpose, multi-object imaging spectrograph.
The Inamori Magellan Areal Camera and Spectrograph (IMACS) will soon be one of the three first-generation instruments for the Magellan 6.5m telescopes. This instrument drove the specification and design of the f/11 Gregorian focus on Magellan, which it uses to feed an all-spherical, refracting wide-field collimator with a 30 arcmin field of view. Two Epps cameras are used to re-image the field of view for imaging and spectroscopy. The aspheric, f/2 ("short") camera images a field of 27 x 27 arcmin at 0.2 arcsec/pixel, and produces 0.32 arcsec images averaged over all field positions across the 0.39 -1.05 micron bandpass. The all-spherical f/4 ("long") camera images a field 15 x 15 arcmin at 0.11 arcsec/pixel, and produces 0.16 arcsec images averaged over all field positions across the 0.365 - 1.0 micron bandpass. This paper describes the final specifications for the multiple spectrographic and imaging modes, and provides a status report on the current state of the instrument project.
The Inamori-Magellan Areal Camera and Spectrograph is nearing completion. This reimaging spectrograph will have fields of view of 15 arcmin and 27 arcmin in its relecting grating and grism spectrographic modes, respectively, the largest such areas available on one of the new generation of large optical-IR ground-based telescopes. In addition to wide field imaging and a range of low- to medium-resolution spectroscopic modes, IMACS will have a 2 × 1000 fiber-fed integral field unit built by Durham University, an ecellette mode, and the potential for a full-field tunable filter. We review some of the planned science programs for IMACS, ranging from spectroscopy of stars in the Galactic halo and nearby dwarf spheroidal galaxies, the search for stars between galaxies, internal kinematics in normal galaxies and AGN, and the evolution of high redshift galaxies and galaxy clusters.
A generation 8-m telescopes, particularly the Keck telescopes in the 1990s have played a crucial role in many scientific programs carried out with the Hubble Space Telescope. The Next Generation Space Telescope, scheduled for launch at the end of this decade, may form a similar relationship with the next generation of ground-based telescopes, for example, CELT, or the NRC Decadal Report's GSMT. Core science programs for ground-based telescopes are now becoming clear. Drawing on these studies, I will address the question of to what degree CELT, GSMT, and perhaps eventually OWL, will share the same important symbiotic relationship to NGST that HST and the 8-m telescopes have enjoyed, or to what extent they will carry out largely independent astronomical research.
The Inamori Magellan Areal Camera and Spectrograph (IMACS) will be one of three first-generation instruments for the Magellan 6.5 m telescopes. It will be installed at the f/11 (Gregorian) Nasmyth focus. This instrument drove the specification and design of the f/11 configuration, which it uses to feed an all-spherical, wide-field collimator. The combination of the Gregorian secondary and refracting collimator lead to 0.2 arc-sec images over a 17 arc-min field with an f/2.66 camera, and 0.4 arc-sec images over a 27 arc- min field with an f/1.49 camera. This paper describes the preliminary specifications for the multiple spectrographic and imaging modes, the optical layout of the instrument and Epps cameras, and strategies for the design and fabrication of the instrument.
The Magellan Project has as its goal the construction of an 8-m aperture optical telescope at Las Campanas, Chile, whose f/1.2 parabolic primary mirror is of borosilicate honeycomb type. The principal configuration of the telescope will be with Cassegrain focus at f/6.26; image sizes are expected to be of the order of 0.25 arcsec rms over the entire field, from 0.33 to 1.10 microns without refocus. An IR Cassegrain focus is planned at f/15, with a chopping secondary of low emissivity. Despite the fast primary-mirror f-ratio, spherical aberration will be acceptably low when chopping is accomplished via rotation of the mirror about its vertex.